1. Technical Field
The present disclosure relates to a lighting apparatus, and more particularly, to a control circuit for a lighting apparatus which uses an LED as a light source.
2. Related Art
A lighting apparatus is designed to use a light source which exhibits high light emission efficiency using a small amount of energy, in order to reduce energy consumption. Representative examples of the light source used in the lighting apparatus may include an LED. The LED is differentiated from other light sources in terms of various aspects such as energy consumption, lifetime, and light quality.
However, since the LED is driven by a current, a lighting apparatus using the LED as a light source requires a large number of additional circuits for current driving. In order to solve the above-described problem, an AC direct-type lighting apparatus has been developed.
The AC-direct type lighting apparatus is configured to convert an AC voltage into a rectified voltage, and drive a current using the rectified voltage such that the LED emits light. Since the AC direct-type lighting apparatus uses a rectified voltage without using an inductor and capacitor, the AC direct-type lighting apparatus has a satisfactory power factor. The rectified voltage indicates a voltage obtained by full-wave rectifying an AC voltage.
The AC direct-type lighting apparatus includes one or more LED groups, and each of the LED group includes one or more LEDs and emits light in response to a change of the rectified voltage.
The lighting apparatus is configured to form a current path corresponding to light emission of the LED group through a driving circuit implemented with an IC.
When a rectified voltage having a higher peak value than a design value is generated because the AC voltage is unstable, a large amount of driving current corresponding to the level of the rectified voltage flow through the current path of the driving circuit. As a result, the driving circuit may be overheated by the driving current corresponding to the rectified voltage having a high peak value.
The overheating of the driving circuit may hinder a stable operation of the lighting apparatus, and damage the driving circuit implemented with an IC. Therefore, current control for the lighting apparatus is needed to prevent the overheating of the driving circuit by a high rectified voltage.